The present invention relates to a process for the preparation of N-sulphonyl-N-(phosphonomethylglycyl) amines which can be used as herbicides.
Products of the following formula are known (European Patent Application 135,454): ##STR3## in which:
R.sup.1 represents a hydrocarbon radical or substituted hydrocarbon radical especially an alkyl, aryl or cycloalkyl radical, the substituents preferably being halogen atoms or phenyl, cyano, alkyl, alkoxy or alkylcarboxylate groups, and the substituents more preferably being halogenated or selected from alkyl groups containing from 1 to 4 carbon atoms; and wherein R.sup.1 preferably contains from 1 to 18 carbon atoms, more preferably from 1 to 7 carbon atoms, and (when R.sup.1 is a cycloalkyl group) more preferably from 3 to 7 carbon atoms, and wherein R.sup.1 is more preferably a chlorinated or fluorinated alkyl radical containing from 1 to 4 carbon atoms, e.g. CF.sub.3 ;
R represents a hydrogen atom or has one of the meanings for R.sup.1, and is preferably an alkyl group containing from 1 to 4 carbon atoms;
R.sup.2 and R.sup.3 each represent a hydrogen atom or are such that OR.sup.2 and OR.sup.3 are groups which can be hydrolyzed; R.sup.2 and R.sup.3 may preferably be an alkyl or aryl radical or substituted alkyl or aryl radical, and more preferably an alkyl radical or substituted alkyl radical; the substituents preferably being those mentioned for R.sup.1, R.sup.2 and R.sup.3 generally containing from 1 to 12 carbon atoms and preferably containing from 1 to 8 carbon atoms; and
R.sup.4 represents a hydrogen atom or a group which can be hydrogenolyzed, represented by R.sup.8, wherein R.sup.8 is preferably a radical of formula Ar(R.sup.5)(R.sup.6)C-- in which Ar is an aromatic group, preferably phenyl, and R.sup.5 and R.sup.6 each are a hydrogen atom or an Ar radical or an alkyl group preferably containing not more than 6 carbon atoms;
and salts of these various products (especially salts of P-OH groups and those of nitrogen atom carrying R.sup.8, which may be catagorized as an ammonium group), especially salts of these products which are acceptable in agriculture. Salts acceptable in agriculture include alkali metal salts, especially sodium and potassium salts, alkaline-earth metal salts, primary, secondary, tertiary or quaternary ammonium salts and sulphonium salts. Other salts of the invention are salts of addition with an acid such as chlorides, sulphates, phosphates and other salts derived from acids with a pK less than or equal to 2.5.
These products can be used as herbicides and/or as intermediates for the synthesis of herbicides.
It is also known to prepare products of the formula ##STR4## in which R, R.sup.1 and R.sup.3 have the same meaning as in formula (I), by a dual operation of hydrolysis and hydrogenolysis of a compound of formula (III): ##STR5## in which:
R, R.sup.1 and R.sup.8 have the same meaning as in formula (I), and R.sup.21 and R.sup.31 have the same meanings as R.sup.2 and R.sup.3, except that R.sup.21 and R.sup.31 do not represent the hydrogen atom.
The preparation of compounds of formula (II) from compounds of formula (III) is carried out by a hydrogenolysis involving the R.sup.8 group and a hydrolysis involving the R.sup.21 and/or R.sup.31 groups.
One object of the invention is to provide a simplified process for the preparation of compounds of formula (I). Another object is to provide a process for the preparation of compounds of formula (I) which does not require hydrolysis.
Other objects and advantages of the invention will become apparent in the course of the description which follows.